We repooted previously that transplantation of approximately 5% of hepatic tissue from normal liver to a UDP-Glycuronyl transferase (UDPGT) deficient Gunn rat liver transfers this enzyme activity into the recipient liver. We predicted thht one of themechanisms of this induced enzyme activity may be due to the survival of a small number of normal hepatocytes in the recipient liver which produced enzyme at a 100% efficiency. To prove or disprove this hypothesis we have done transplantation experiments with radioactively labelled donor liver. Autoradiographic study of serial hepatic sections at different time intervals after transplantation suggest that approximately 0.9% of the transplanted cells survive in the host liver at least up to 12 weeks following grafting. The results suggest that the observed UDPCT activity in the Gunn rat after transplantation of normal liver may partially be due to these cells.